Nate Brunelle Today: Dictionaries CS1110 Nate Brunelle Today: Dictionaries

Questions?

Tips for fixing bugs in code Know what your code should do Read error messages Believe the error message Print every variable Binary search Test more Look for “code coverage”

Binary search Start: a line you know is before the bug End: a line you know is after the bug Middle: the line halfway between start and end Check whether Middle has the bug. If so, then Middle is the new End. Otherwise if Middle has no bug, then Middle is the new Start. You just ruled out half of the remaining lines of code as the bad ones! Keep going until you have only 1 line of code left. That one has the bug.

Test Cases Try winning: fun, f, u, n Capital: FUN, f, u ,n 1234, 1 Fun, fn, Fun, x, x, x, x, x, x F_n, n, _

Collections Order doesn’t matter, No Repetition Order Matters, Repetition ok Examples: String List Tuple Range Counting starts at 0 collection[index] gives a specific value in the collection Order doesn’t matter, No Repetition Examples: Set Dict Map Table

Set Things are unordered Cannot have repetition

Dict A set of key:value mappings d = { } d[‘name’] = 1 d[‘name’]

Dict Somewhat like variables, somewhat like a list

Dict is like variables Gives names to values Create using = Reassign using = Easy to go from name to a value Very hard to go from value to name

Dict is like a list Index to access members Index must be an int Key to access members Key can be any immutable type No rules for values of keys To add in a new thing: d[key] = … Index to access members Index must be an int Indexes cannot be skipped To add in a new thing: lst.append(…)